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  3. Sometimes you can know too much. The aim of screening healthy people for cancer is to discover tumors when they are small and tr

Sometimes you can know too much. The aim of screening healthy people for cancer is to discover tumors when they are small and tr

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问题     Sometimes you can know too much. The aim of screening healthy people for cancer is to discover tumors when they are small and treatable. It sounds laudable and often it is. But it sometimes leads to unnecessary treatment. The body has a battery of mechanisms for stopping small tumors from becoming large ones. Treating those that would have been suppressed anyway does no good and can often be harmful.
    Take lung cancer. A report in this week’s Journal of the American Medical Association, by Peter Bach of the Memorial Sloan-Kettering Cancer Centre in New York and his colleagues, suggests that, despite much fanfare around the use of computed tomography(CT)to detect tumors in the lungs well before they cause symptoms, the test may not reduce the risk of dying from the disease at all—indeed, it may make things worse.
    The story begins last year, when Claudia Henschke of Cornell University and her colleagues made headlines with a report that patients whose lung cancer had been diagnosed early by CT screening had excellent long-term survival prospects. Her research suggested that 88% of patients could expect to be alive ten years after their diagnosis. Dr. Bach found similar results in a separate study. In his case, 94% of patients diagnosed with early-stage lung cancer were alive four years later.
    Survival data alone, though, fail to answer a basic question: "compared with what?" People are bound to live longer after their diagnosis if that diagnosis is made earlier. Early diagnosis is of little value unless it results in a better prognosis.
    Dr. Bach, therefore, interrogated his data more thoroughly. He used statistical models based on results from studies of lung cancer that did not involve CT screening, to try to predict what would have happened to the individuals in his own study if they had not been part of that study The results were not encouraging.
    Screening did, indeed, detect more tumors. Over the course of five years, 144 cases of lung cancer were picked up in a population of 3,200, compared with a predicted number of 44. Despite these early diagnoses, though, there was no reduction in the number of people who went on to develop advanced cancer, nor a significant drop in the number who died of the disease(38, compared with a prediction of 39). Considering that early diagnosis prompted a tenfold increase in surgery aimed at removing the cancer(the predicted number of surgical interventions was 11; the actual number was 109), and that such surgery is unsafe—5% of patients die and another 20-40% suffer serious complications—the whole process seems to make things worse.
The author quotes the example of Claudia Henschke’s report in Paragraph 3 to______.
选项 A、refute his statement in the Paragraphs 1 and 2
B、prove the fact that early screened patients can live longer
C、to pave the way for declaring that early diagnose doesn’t help much
D、to state cancers picked up by CT screening cause clinical disease
答案C
解析 属逻辑关系题。克劳迪娅·赫恩施克的报告看似与作者前两段所表述的观点相悖，认为患者经CT早期诊断为肺癌后，长期生存率显著提高，但其实是为下文做铺垫。作者在第四段谈到了早期诊断无疑可延长生存期，但早期诊断后患者预后必须良好，否则早期诊断就几乎无任何价值，所以引用克劳迪娅·赫恩施克的报告是为下文做铺垫。A和B项只是表面的现象，D项在文中并没有提及。故正确答案为C。
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